In what was described as likely the first and last court proceeding to be undertaken under provisions of an old version of Canada’s Patent Act, the Federal Court of Appeal upheld a lower court’s decision that failure to pay the full fee for the patent of a medication did not render the patent invalid.

The appeal in Apotex Inc. v. Pfizer Inc. 2017 FCA 201, delivered Oct. 2, deals with the drug latanoprost, sometimes marketed as Xalatan. It is used to treat pressure in the eye,...